1. Field of the Invention
The present invention relates to a connector module for leading out signal lines from a back surface of an integrated circuit device, and to an integrated circuit device suitable for use with the connector module.
2. Description of Related Art
High speed signal input and output with respect to a semiconductor integrated circuit device mounted on a printed wiring board are generally achieved through micro-strip lines or strip lines provided in the wiring board. More specifically, the printed wiring board is constructed in a multi-level structure for the provision of the strip lines and the micro-strip lines, which are employed as impedance-matched transmission paths.
With the aforesaid arrangement, however, the dielectric constant of the printed wiring board, the capacitance and inductance of an interconnection pattern and the like should properly be conditioned for the high speed signal transmission. This requires advanced techniques for system development and design. In addition, a consideration should be given to an arrangement for overcoming drawbacks associated with noises and crosstalk and, hence, there are technical and economic problems.
Further, various semiconductor devices operative at different source voltages should be employed for operation of a high-speed system. Accordingly, a plurality of layers are separately provided in the printed wiring board for applying the different source voltages to the respective semiconductor devices. However, this arrangement deteriorates the electrical properties of the signal transmission paths and, when directed to the high-speed system, encounters technical difficulties. In addition, this arrangement may cause noises and crosstalk, which hinder the speed-up of the system.
An LVDS (low-voltage differential signaling) interface, for example, is employed for high speed data transmission in a liquid crystal display device. The LVDS interface is a small-amplitude and high-speed differential interface specified by EIA644/IEEE1596.3, and applicable to communications at frequencies up to 500 MHz. An LVDS-conformable differential driver (semiconductor device), which incorporates circuits for four channels, for example, achieves a data transmission rate of 400 Mbps by outputting 100-MHz differential signals from the respective channels.
Where such an LVDS differential driver device is to be mounted on a printed wiring board, a pseudo-coaxial circuit should be provided for elimination of crosstalk and noises by forming micro-strip lines on the printed board so that ground lines are disposed between signal lines.
However, the pseudo-coaxial circuit does not provide perfect coaxial transmission paths, so that crosstalk and noises are inevitably introduced even if the pseudo-coaxial circuit is provided on the multi-level printed wiring board. As a result, signals transmitted at a high transmission rate through the pseudo-coaxial circuit on the wiring board do not have sharp square waveforms. Therefore, this arrangement is not necessarily adaptable to applications for high speed digital data transmission.
Similar problems arise in the field of personal computers which are increasingly directed to higher speed operation. That is, a frequency employed for signal transmission between a CPU and a chip set is currently about 133 MHz to about 200 MHz, but will doubtlessly be increased to about 400 MHz to about 800 MHz. On the other hand, it is doubtful that the existing techniques for printed wiring boards can cope with such high speed signal transmission.
It is an object of the present invention to provide a connector module which realizes a connection structure adapted for higher speed signal transmission with respect to an integrated circuit device.
It is another object of the invention to provide an integrated circuit device having the aforesaid connector module.
It is further another object of the invention to provide an integrated circuit device having a construction suitable for attachment with the connector module.
The present invention is directed to a connector module (30, 30A, 30B) which is to be connected to an integrated circuit device (50, 50A, 50B) having rear electrodes (52) provided on a back surface (51) thereof facing away from a wiring board (70). The connector module includes a connector (1, 1A, 1B) having contacts (15) to be electrically connected to the rear electrodes, and a fixture structure (2, 2A, 2B, 12, 12A, 12B) for fixing the connector to the integrated circuit device.
Parenthesized alphanumeric characters denote corresponding components to be described later in embodiments of the invention, but do not intend to limit the invention to the embodiments. This definition is effectual in this section.
In the present invention, high speed signal transmission with respect to the integrated circuit device having the rear electrodes provided on the back surface thereof opposite from the board-opposed surface is achieved through external circuitry provided outside the wiring board. More specifically, the inventive connector module leads signal lines out of the integrated circuit device by attaching the connector thereof to the integrated circuit device with the contacts thereof connected to the rear electrodes of the integrated circuit device. Thus, transmission paths are provided outside the wiring board, so that the influences of inter-signal crosstalk and noises can be eliminated for proper high speed signal transmission.
Particularly where signals to be transmitted at a frequency of not lower than 50 MHz are allocated to signal lines led out of the device with the use of the connector module, the aforesaid effects are notable.
The integrated circuit device may have electrodes (63, 64) provided on the board-opposed surface thereof in addition to the rear electrodes (52) provided on the back surface thereof. In this case, high speed signal transmission can advantageously be achieved through the signal transmission paths outside the wiring board by allocating signals required to be transmitted at a high speed (e.g., higher than 50 MHz) to the rear electrodes.
The connector module may further include a wiring ember (3, 90) connected to the connector.
With this arrangement, the wiring member connected to the connector allows for signal transmission with respect to any other electronic devices via the transmission paths outside the wiring board.
The wiring member preferably has a pseudo-coaxial structure.
With this arrangement, the signal transmission paths are free from the influences of the inter-signal crosstalk and noises.
In this case, the pseudo-coaxial structure may be constituted by micro-strip lines and strip lines arranged such that signal lines are provided between ground lines or, alternatively, by twisted-pair cables.
The fixture structure preferably includes a connection block (2, 2A, 2B) which is fixable to the back surface of the integrated circuit device and engageable with the connector.
With this arrangement, electrical connection between the contacts of the connector and the rear electrodes of the integrated circuit device can be established by fixing the connection block to the back surface of the integrated circuit device and bringing the connection block into engagement with the connector.
The fixture structure preferably further includes lock mechanism (12, 22; 12A, 12B, 24) for keeping the connector and the connection block in engagement with each other.
With this arrangement, the connector and the connection block can be kept in engagement with each other by the lock mechanism, so that the electrical connection between the connector module and the integrated circuit device can assuredly be maintained. This ensures the reliability of the signal transmission paths outside the wiring board.
The connection block preferably incorporates a cooling mechanism (80) for cooling the integrated circuit device.
With this arrangement, sufficient heat dissipation from the integrated circuit device can be achieved by the cooling mechanism incorporated in the connection block attached to the back surface of the integrated circuit device. Thus, the inventive connector module can be applied to an integrated circuit device generating a greater amount of heat to provide signal transmission paths outside the wiring board.
The cooling mechanism may be radiator fins provided on the connection block to allow the connection block to double as a heat sink. The cooling mechanism may be a cooling fan provided in the connection block.
An integrated circuit device according to the present invention includes an integrated circuit device body having rear electrodes provided on a back surface thereof facing away from a wiring board, and the aforesaid connector module attached to the back surface of the integrated circuit device body.
With this arrangement, the integrated circuit device can receive and transmit signals via the signal transmission paths outside the wiring board. Thus, high speed signal transmission can be achieved through the advantageous signal transmission paths provided outside the wiring board with little limitation, so that the integrated circuit device can operate at a higher speed.
An integrated circuit device according to one embodiment of the present invention includes an integrated circuit device body having rear electrodes provided on a back surface thereof facing away from a wiring board, and a connection block fixed to the back surface of the integrated circuit device body for engagement with a connector having contacts to be electrically connected to the rear electrodes.
In accordance with the present invention, the connection block is fixed to the back surface of the integrated circuit device body. Therefore, the integrated circuit device can easily utilize the signal transmission paths outside the wiring board by connecting the connector of the connection module to the connection block.
The connection block may be formed integrally with a mold resin portion of the integrated circuit device. Alternatively, the connection block may be a separate member from the mold resin portion of the integrated circuit device, and fixed to the integrated circuit device body with an adhesive, by ultrasonic fusion bonding or by proper fixing means such as engagement claws.
The foregoing and other objects, features and effects of the present invention will become more apparent from the following description of the preferred embodiments with reference to the attached drawings.